package com.likou.second_challenge;

public class q21 {

    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
        ListNode ans = new ListNode(0);
        ListNode p = ans;
        ListNode p1 = list1;
        ListNode p2 = list2;

        while (p1 != null && p2 != null) {
            if (p1.val <= p2.val) {
                p.next = new ListNode(p1.val);
                p1 = p1.next;
                p = p.next;
            } else {
                p.next = new ListNode(p2.val);
                p2 = p2.next;
                p = p.next;
            }
        }

        if (p1 == null) {
            p.next = p2;
        } else {
            p.next = p1;
        }

        return ans.next;
    }
}
